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mm: replace access_process_vm() write parameter with gup_flags

This removes the 'write' argument from access_process_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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lorenzo-stoakes authored and torvalds committed Oct 13, 2016
1 parent 6347e8d commit f307ab6dcea03f9d8e4d70508fd7d1ca57cfa7f9
@@ -157,14 +157,16 @@ put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
static inline int
read_int(struct task_struct *task, unsigned long addr, int * data)
{
int copied = access_process_vm(task, addr, data, sizeof(int), 0);
int copied = access_process_vm(task, addr, data, sizeof(int),
FOLL_FORCE);
return (copied == sizeof(int)) ? 0 : -EIO;
}
static inline int
write_int(struct task_struct *task, unsigned long addr, int data)
{
int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
int copied = access_process_vm(task, addr, &data, sizeof(int),
FOLL_FORCE | FOLL_WRITE);
return (copied == sizeof(int)) ? 0 : -EIO;
}
@@ -281,7 +283,8 @@ long arch_ptrace(struct task_struct *child, long request,
/* When I and D space are separate, these will need to be fixed. */
case PTRACE_PEEKTEXT: /* read word at location addr. */
case PTRACE_PEEKDATA:
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
copied = access_process_vm(child, addr, &tmp, sizeof(tmp),
FOLL_FORCE);
ret = -EIO;
if (copied != sizeof(tmp))
break;
@@ -271,7 +271,7 @@ long arch_ptrace(struct task_struct *child, long request,
case BFIN_MEM_ACCESS_CORE:
case BFIN_MEM_ACCESS_CORE_ONLY:
copied = access_process_vm(child, addr, &tmp,
to_copy, 0);
to_copy, FOLL_FORCE);
if (copied)
break;
@@ -324,7 +324,8 @@ long arch_ptrace(struct task_struct *child, long request,
case BFIN_MEM_ACCESS_CORE:
case BFIN_MEM_ACCESS_CORE_ONLY:
copied = access_process_vm(child, addr, &data,
to_copy, 1);
to_copy,
FOLL_FORCE | FOLL_WRITE);
break;
case BFIN_MEM_ACCESS_DMA:
if (safe_dma_memcpy(paddr, &data, to_copy))
@@ -147,7 +147,7 @@ long arch_ptrace(struct task_struct *child, long request,
/* The trampoline page is globally mapped, no page table to traverse.*/
tmp = *(unsigned long*)addr;
} else {
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp))
break;
@@ -279,7 +279,7 @@ static int insn_size(struct task_struct *child, unsigned long pc)
int opsize = 0;
/* Read the opcode at pc (do what PTRACE_PEEKTEXT would do). */
copied = access_process_vm(child, pc, &opcode, sizeof(opcode), 0);
copied = access_process_vm(child, pc, &opcode, sizeof(opcode), FOLL_FORCE);
if (copied != sizeof(opcode))
return 0;
@@ -453,7 +453,7 @@ ia64_peek (struct task_struct *child, struct switch_stack *child_stack,
return 0;
}
}
copied = access_process_vm(child, addr, &ret, sizeof(ret), 0);
copied = access_process_vm(child, addr, &ret, sizeof(ret), FOLL_FORCE);
if (copied != sizeof(ret))
return -EIO;
*val = ret;
@@ -489,7 +489,8 @@ ia64_poke (struct task_struct *child, struct switch_stack *child_stack,
*ia64_rse_skip_regs(krbs, regnum) = val;
}
}
} else if (access_process_vm(child, addr, &val, sizeof(val), 1)
} else if (access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(val))
return -EIO;
return 0;
@@ -543,7 +544,8 @@ ia64_sync_user_rbs (struct task_struct *child, struct switch_stack *sw,
ret = ia64_peek(child, sw, user_rbs_end, addr, &val);
if (ret < 0)
return ret;
if (access_process_vm(child, addr, &val, sizeof(val), 1)
if (access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(val))
return -EIO;
}
@@ -559,7 +561,8 @@ ia64_sync_kernel_rbs (struct task_struct *child, struct switch_stack *sw,
/* now copy word for word from user rbs to kernel rbs: */
for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) {
if (access_process_vm(child, addr, &val, sizeof(val), 0)
if (access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE)
!= sizeof(val))
return -EIO;
@@ -1156,7 +1159,8 @@ arch_ptrace (struct task_struct *child, long request,
case PTRACE_PEEKTEXT:
case PTRACE_PEEKDATA:
/* read word at location addr */
if (access_process_vm(child, addr, &data, sizeof(data), 0)
if (access_process_vm(child, addr, &data, sizeof(data),
FOLL_FORCE)
!= sizeof(data))
return -EIO;
/* ensure return value is not mistaken for error code */
@@ -493,7 +493,8 @@ unregister_all_debug_traps(struct task_struct *child)
int i;
for (i = 0; i < p->nr_trap; i++)
access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]),
FOLL_FORCE | FOLL_WRITE);
p->nr_trap = 0;
}
@@ -537,7 +538,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc)
unsigned long next_insn, code;
unsigned long addr = next_pc & ~3;
if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0)
if (access_process_vm(child, addr, &next_insn, sizeof(next_insn),
FOLL_FORCE)
!= sizeof(next_insn)) {
return -1; /* error */
}
@@ -546,7 +548,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc)
if (register_debug_trap(child, next_pc, next_insn, &code)) {
return -1; /* error */
}
if (access_process_vm(child, addr, &code, sizeof(code), 1)
if (access_process_vm(child, addr, &code, sizeof(code),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(code)) {
return -1; /* error */
}
@@ -562,7 +565,8 @@ withdraw_debug_trap(struct pt_regs *regs)
addr = (regs->bpc - 2) & ~3;
regs->bpc -= 2;
if (unregister_debug_trap(current, addr, &code)) {
access_process_vm(current, addr, &code, sizeof(code), 1);
access_process_vm(current, addr, &code, sizeof(code),
FOLL_FORCE | FOLL_WRITE);
invalidate_cache();
}
}
@@ -589,7 +593,8 @@ void user_enable_single_step(struct task_struct *child)
/* Compute next pc. */
pc = get_stack_long(child, PT_BPC);
if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
if (access_process_vm(child, pc&~3, &insn, sizeof(insn),
FOLL_FORCE)
!= sizeof(insn))
return;
@@ -70,7 +70,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
copied = access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 0);
sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp))
break;
ret = put_user(tmp, (u32 __user *) (unsigned long) data);
@@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
ret = 0;
if (access_process_vm(child, (u64)addrOthers, &data,
sizeof(data), 1) == sizeof(data))
sizeof(data),
FOLL_FORCE | FOLL_WRITE) == sizeof(data))
break;
ret = -EIO;
break;
@@ -74,7 +74,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
copied = access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 0);
sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp))
break;
ret = put_user(tmp, (u32 __user *)data);
@@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
break;
ret = 0;
if (access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 1) == sizeof(tmp))
sizeof(tmp),
FOLL_FORCE | FOLL_WRITE) == sizeof(tmp))
break;
ret = -EIO;
break;
@@ -131,7 +131,7 @@ read_tsk_long(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, res, sizeof(*res), 0);
copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
return copied != sizeof(*res) ? -EIO : 0;
}
@@ -142,7 +142,7 @@ read_tsk_short(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, res, sizeof(*res), 0);
copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
return copied != sizeof(*res) ? -EIO : 0;
}
@@ -153,7 +153,8 @@ write_tsk_short(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, &val, sizeof(val), 1);
copied = access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE);
return copied != sizeof(val) ? -EIO : 0;
}
@@ -164,7 +165,8 @@ write_tsk_long(struct task_struct *child,
{
int copied;
copied = access_process_vm(child, addr, &val, sizeof(val), 1);
copied = access_process_vm(child, addr, &val, sizeof(val),
FOLL_FORCE | FOLL_WRITE);
return copied != sizeof(val) ? -EIO : 0;
}
@@ -127,7 +127,8 @@ static int get_from_target(struct task_struct *target, unsigned long uaddr,
if (copy_from_user(kbuf, (void __user *) uaddr, len))
return -EFAULT;
} else {
int len2 = access_process_vm(target, uaddr, kbuf, len, 0);
int len2 = access_process_vm(target, uaddr, kbuf, len,
FOLL_FORCE);
if (len2 != len)
return -EFAULT;
}
@@ -141,7 +142,8 @@ static int set_to_target(struct task_struct *target, unsigned long uaddr,
if (copy_to_user((void __user *) uaddr, kbuf, len))
return -EFAULT;
} else {
int len2 = access_process_vm(target, uaddr, kbuf, len, 1);
int len2 = access_process_vm(target, uaddr, kbuf, len,
FOLL_FORCE | FOLL_WRITE);
if (len2 != len)
return -EFAULT;
}
@@ -505,7 +507,8 @@ static int genregs32_get(struct task_struct *target,
if (access_process_vm(target,
(unsigned long)
&reg_window[pos],
k, sizeof(*k), 0)
k, sizeof(*k),
FOLL_FORCE)
!= sizeof(*k))
return -EFAULT;
k++;
@@ -531,12 +534,14 @@ static int genregs32_get(struct task_struct *target,
if (access_process_vm(target,
(unsigned long)
&reg_window[pos],
&reg, sizeof(reg), 0)
&reg, sizeof(reg),
FOLL_FORCE)
!= sizeof(reg))
return -EFAULT;
if (access_process_vm(target,
(unsigned long) u,
&reg, sizeof(reg), 1)
&reg, sizeof(reg),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(reg))
return -EFAULT;
pos++;
@@ -615,7 +620,8 @@ static int genregs32_set(struct task_struct *target,
(unsigned long)
&reg_window[pos],
(void *) k,
sizeof(*k), 1)
sizeof(*k),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(*k))
return -EFAULT;
k++;
@@ -642,13 +648,15 @@ static int genregs32_set(struct task_struct *target,
if (access_process_vm(target,
(unsigned long)
u,
&reg, sizeof(reg), 0)
&reg, sizeof(reg),
FOLL_FORCE)
!= sizeof(reg))
return -EFAULT;
if (access_process_vm(target,
(unsigned long)
&reg_window[pos],
&reg, sizeof(reg), 1)
&reg, sizeof(reg),
FOLL_FORCE | FOLL_WRITE)
!= sizeof(reg))
return -EFAULT;
pos++;
@@ -57,7 +57,8 @@ static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
unsigned char opcode[15];
unsigned long addr = convert_ip_to_linear(child, regs);
copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
copied = access_process_vm(child, addr, opcode, sizeof(opcode),
FOLL_FORCE);
for (i = 0; i < copied; i++) {
switch (opcode[i]) {
/* popf and iret */
@@ -36,7 +36,8 @@ int is_syscall(unsigned long addr)
* slow, but that doesn't matter, since it will be called only
* in case of singlestepping, if copy_from_user failed.
*/
n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
n = access_process_vm(current, addr, &instr, sizeof(instr),
FOLL_FORCE);
if (n != sizeof(instr)) {
printk(KERN_ERR "is_syscall : failed to read "
"instruction from 0x%lx\n", addr);
@@ -212,7 +212,8 @@ int is_syscall(unsigned long addr)
* slow, but that doesn't matter, since it will be called only
* in case of singlestepping, if copy_from_user failed.
*/
n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
n = access_process_vm(current, addr, &instr, sizeof(instr),
FOLL_FORCE);
if (n != sizeof(instr)) {
printk("is_syscall : failed to read instruction from "
"0x%lx\n", addr);
@@ -1266,7 +1266,8 @@ static inline int fixup_user_fault(struct task_struct *tsk,
}
#endif
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
unsigned int gup_flags);
extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
void *buf, int len, unsigned int gup_flags);
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